Terminal support for bayonet type coaxial connector



Feb. 12, 1957 D. cs. ARMSTRONG 2,781,500

TERMINAL SUPPORT FOR, BAYONET TYPE COAXIAL CONNECTOR Filed April 9, 1955 m WM 2 V. H mm N .H n .4 W 0 v J Y/w B4 United States Patent TERMINAL SUPPORT FOR BAYONET TYPE COAXIAL CONNECTOR David G. Armstrong, West Newton, Mass., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application April 9, 1953, Serial No. 347,805

2 Claims. (Cl. 339-177) This invention relates to a crystal detector assembly and more particularly to a crystal detector assembly which is adapted to be used at the terminal of a waveguide.

In the prior art the crystal detector assembly was connected to an output circuit through a type N or Amphenol output connector. The type N connector has an effective usefulness up to 10,000 megacycles. However it is somewhat cumbersome to use. Where the operational frequency does not extend beyond the 4,000 megacycle range of the type BNC connector has been found to have several advantages over the type N connector. The type BNC connector is of considerably smaller size than the type N connector for which it may be substituted. In addition, it takes much less time to assemble the type BNC connector. Also, because of its included locking feature, the elements of the type BNC connector are readily retained in properly assembled relationship.

Type N and type BNC connectors are coaxial connectors; the former is a screw type connector and the latter is a bayonet twist lock connector.

Information on the types N and BNC connectors may be found in the publication Armed Services Index of R. F. Transmission Lines and Fittings, ASESA 49-2B (Navships 9004023), Nov. 1, 1952, issued by the Armed Services Electro Standards Agency.

This invention marks a departure from the prior art by providing a crystal detector assembly for a waveguide which is adapted to be used with a type BNC connector. The invention includes a coaxial crystal mounting arrangement for cartridge type crystals which includes a central conductor and a concentric outer conductor separated from the inner conductor by a suitable insulator with both conductors being held in assembled relationship by means of a properly designed nut for threaded engagement with a threaded support member and wherein the nut serves the additional purpose of aiding in assembly.

An object of this invention is to provide an improved crystal mount assembly.

A A further object is to provide an improved crystal mount assembly which is adapted to be used with a type BNC connector.

A further object is to provide a crystal mount assembly which includes means for receiving a type BNC connector without sacrificing any useful features known to the prior art.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a side view of the crystal mount with the Waveguide and parts of the crystal detector assembly shown in section,

Fig. 2 is a plan view of the device shown in Fig. 1, and

Figs. 3-5 are perspective views of the crystal mount in various stages of assembly.

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The embodimentof the invention shown in the drawing is directed to the use of a cartridge type crystal as a microwave detector, the crystal being physically mounted in a rectangular waveguide for coupling the waveguide to a coaxial cable. In Fig. 1 there is shown a waveguide 12 terminating in an end plate 13. A cartridge type crystal detector unit 14 of the type known as JAN 1N27 comprising a tubular portion 15 of insulating ma terial housing the crystal which is shown diagrammatically at 17 is mounted in the waveguide. One end of the cartridge type crystal 14 is terminated in a flanged tip terminal 19. The other end is closed by a sleevelike member 21 of conducting material which terminates in a radial flange 22.

The cartridge type crystal 14 is mounted centrally of the wide sides of the waveguide and at a distance approximately equal to a quarter wave length at the operating frequency from the end plate 13. The bottom side of the waveguide 12 is provided with a bore 24 wherein there is secured by suitable means the reduced axial portion of a cylindrical stub-like member 26. The cylindrical stub-like member 26 is threaded along its entire outside surface and is provided with a radially inwardly projecting lip 27. An inside threaded cap 29 for threaded engagement with member 26 is adapted to clamp the radial projecting flange 22 of the crystal cartridge 14 between the inside end surface of the cap 29 and the outer surface of the lip 27. By this arrangement it is a relatively easy matter to replace the crystal by simply removing the cap 29 and withdrawing the crystal by manually gripping the radial flange 22.

The annular space between the stub-like member 26 and the sleeve portion 21 of the crystal 14 is designed to facilitate impedance matching in the waveguide in a manner well known in the art. The foregoing description has been directed to structural details which are not novel and do not constitute the invented features of this disclosure.

The upper one of the wide sides of the waveguide 12 as seen in Fig. l is provided with a bore 31 which is in axial alignment with the bore 24. A cylindrical support member 33 which is considerably longer than and of greater diameter than the cylindrical stub-like member 26 but which is reduced at one end thereof in the same manner as the member 26 is mounted in the bore 31 of the waveguide 12. The cylindrical support member 33 intermediate its ends has a short section 34 of reduced inside diameter which serves as a mounting abutment. Intermediate this short section 34 of reduced diameter and the end of member 33 opposite that which is mounted in the waveguide section 12 is an internally threaded portion. Between the reduced diameter section and the end of the cylindrical member 33 mounted in the waveguide 12 is a stepped passage 36. Mounted in said stepped passage 36 is a flanged sleeve 37. "Dhe flange 38 of the sleeve 37 is of such thickness so as to seat in the portion of the passage 36 extending to the step. After assembly of the foregoing the inside surface of the waveguide 12 remains flush.

An insulating washer 41 is provided adjacent the section 34 of reduced diameter. Extending through the central opening of the washer 41 is a central cylindrical conductor 42. The central cylindrical conductor 42 may be machined from solid bar stock so as to provide a flange 43 and a reduced end portion 44. Each of the ends of the cylindrical conductor 42 is bored and slotted as at 45 and 46 so as to provide spring finger sockets.

An elongated insulating member 51 slips over the end 45 of the central cylindrical conductor 42 so as to completely isolate the conductor 42 from the concentric mounting members. An adaptor 53 having a threaded radial flange 54 is adapted 'to slip over the insulator 51 and tlrreadedly "engage "the inside surface of the cylindrical member 33. The end of the adaptor 53 opposite t9 t fl n P ti n 4 i id d Wi Pa 1 f metnica lly opposite extennai pins 55. The inside surface of the 'adapto-r53 at'thissame end is reduced'ancltape-red. The'inside'end port-ion of ithegadaptorsfi with the insula- "tor 51"forn1s an annular opening which extends axially substantially the same distance as doesthe slotted end -45 Of'the'center conductor 42. .A locknut56 is provided having a.flange 57-which'flange isreduoed at two diametrically opposite portions .of the periphery to provide a pair of parallel flat sections 58 so that an ordinary open 'end wrench maybe usedfto tighten down the. nut against the1adaptor' 53. The inside of "l'ooknut56 is provided with mo -lon itudinally extending slots'61 by means of: which-the loc'knnt may beslipped over the pins 55 on the adaptor 53.

'The assembled crystal mount as shown and described is adapted to receive a {BNC connector. The use of "BNCconnectors in many applications is currently becom- "ing increasingly common. Since the output of a crystal mixer:or detector contains no high frequency component, ENC connectors are as satisfactory as the larger and "more awkward type N connectors for this purpose.

'Figs. 3, 4, and 5 show the nut 56 in progressive stages of assembly. The nut 56 is slipped/over the pins 55 and "sliding downbetween the adaptor 53 and the cylindrical member 313 threadably engages theinsidesurface of the cylindrical member 33. A wrench (not shown) may be used for the final turn of the nutj'56.

Theannular opening that remains in the stepped pas- "sa ge36after assembly is designed, to minimize leakage in a manner that is conventional and well known in the art. Furthermore though not clearly shown in the draw- 3 ing; the proper ratio of diameters between the concentric conductors will give proper impedance match and minimum'loss. No discussion of this is made since it is likewise known to the art.

In operation, the waveguide is provided adjacent its 4.

'ends with two coaxial bores through its opposite wide sides. Opposit'cly mounted in said bores are a cylindripcal member 33 and a cylindrical member 26. The center conductor 42 with the insulating washer 41 slipped over its lower end is inserted through the reduced section &

34. The insulator 51 is slipped over the center conductor 42 following which the adaptor 53 is threaded into the cylindrical member 33 until it abuts the flange of the insulator 51 finger tight. Subsequently and as shown in Figs. 3, 4, and 5 the ioclrnut 56 is slipped over the end threaded into it. The final tightening operation of the 'n ut may be performed by means of a wrench.

' The crystal mount described is similar t-oroonventional xcrystal mountshaving type Nor Amphenol output connectors. The outer conductor section referred to as the adaptor in the specification and the center conductor may --be designed tomeet standard specifications -for --a -ferna'le BNC connector. The two-pins 55 on the adaptor are so located as to fit into a pair of spiral slots in the mating BNC cable connector.

Obviously many modifiqations and variations of the present invention are possiblein the light of the above teachings. It-is thereforeto be understood thatnwithin the scope of the appended claims the invention may be practiced otherwise than specifically described.

I claim:

1. An improved terminal device adapted to housed with a bayonet type coaxial connector, said terminal de vice comprising; .a support. member formed .withan axial opening threaded.. adjacent,one end and formed with an inside flange intermediate the ends of the opening; an insulator washer on the flange; a center conductor formed with a flange intermediate its endsfor abutting said insulator washer; a tubular insulator formed with a flange at one end for'buttingup against the fiange of said center conductor; a tubular adaptor formed at one end with a threaded flange and toward its other end with a pair of .Oppo se'dpin-like projections on its outer surface, the pinlike projections adapted to register with a pair of spiral slots in a mating male bayonet type coaxial cable connector; and an externally threaded locknut formed at one end with anexternaltightening flange with opposed flats and formed internally with opposed longitudinal slots for registration with the pin-like projections on said tubular adaptor.

2. lmprovementsjin a terminal device, adapted to be used witha bayonet type coaxial connector, wherein the terminal device includes asupport member formed with an axial openingland an inside flange intermediatejthe en-dsot theopening, an insulator washer on the flange, a center conductor "formed with a flange intermediate its 'ends for abutting the insulator washer, a tubular'insulater formed withaflange at one end forbutting up against the flange ,of the center conductor; ,said improvements comprising a tubular adaptor formed atone end with athreaded'flange and toward its other end witha pair of pin-like projections on its outer surface, the pinlike projections adapted to register with a pair of spiral slots in a mating male bayonet type coaxial connector, and an externally threaded locknut formed at one end with an external tightening flange with OPP Sed flats and formed internally with pposed longitudinal slots for registrationwithithe pin-like projections onsaid tubular adaptor.

References Cited in the file of this patent UNIT-ED STATESPATENTS 1,- 933',272 Leuvelink Oct. 31, 1933 2,425,834 Salisbury Aug. 19, 1947 2,438,521 Sharpless Mar. 30,1948 2,484,256 Vaughan Oct. 11, 1949 2,587,055 .Marshall Feb. 26, 1952 2,649,544 "Zalcski Aug. 18, 1953 

